Electromagnetic pump or motor device with axially spaced piston members

ABSTRACT

An electromagnetic pump or motor device includes a cylinder having a bore selectively sealed at its ends by removable valve plate assemblies communicating with a fluid system, a piston assembly movable in the bore of the cylinder, and spaced solenoid coils removably accurately positioned about the cylinder by a central radially outwardly projecting annular rib having two stop faces against which the inner ends of the coil housings abut, said solenoid coils being alternately energized to produce respective magnetic fields alternately for attracting the piston assembly to reciprocate the same in the bore. The piston assembly includes two spaced cylindrical pistons joined by a non-magnetic connecting pin or coupling, the piston assembly being of sufficient length to position a part of one piston radially inside the non-energized coil at the end of the piston assembly stroke, whereby such one piston is in a strong magnetic field for the return stroke of the cycle.

United States Patent 91 Farkos Feb. 12, 1974 Inventor: Robert A. Farkos,63 York Rd., Hudson, Ohio 44236 Filed: May 24, 1973 Appl. No.: 363,332

U.S. Cl. 417/418 1 [51] Int. Cl. F04b 17/04 [58] Field of Search 417/50,417, 418; 310/24 [56] References Cited UNITED STATES PATENTS 2,515,1107/1950 Bornstein 417/418 2,690,128 9/1954 Basilewsky... 417/4182,988,264 6/1961 Reutter 417/418 3,103,603 9/1963 Reutter 417/4183,134,938 5/1964 Morgan 417/418 3,282,219 11/1966 Blackwell et a1.417/418 3,286,911 11/1966 Clarke 417/418 3,459,132 8/1969 Meyer 417/4173,740,171 6/1973 Farkos 417/418 Primary Examiner-C. .l. l-lusarAttorney, Agent, or Firm-Donnelly, Maky, Renner & Otto [5 7] ABSTRACT Anelectromagnetic pump or motor device includes a cylinder having a boreselectively sealed at its ends by removable valve plate assembliescommunicating with a fluid system, a piston assembly movable in the boreof the cylinder, and spaced solenoid coils removably accuratelypositioned about the cylinder by a central radially outwardly projectingannular rib having two stop faces against which the inner ends of thecoil housings abut, said solenoid coils being alternately en- 9 Claims,2 Drawing FEES ELECTROMAGNETIC PUMP OR MOTOR DEVICE WITH AXIALLY SPACEDPISTON MEMBERS The present invention relates as indicated to anelectromagnetic pump or motor device and more particularly to anelectromagnetic pump having axially spaced solenoid coils about acylinder operative to reciprocate a piston assembly having axiallyspaced piston members. Such electromagnetic pump is, in some respects,similar to the pump or motor device disclosed in my copendingapplication Ser. No. 170,448, filed Aug. 10, 1971, now US. Pat. No.3,740,171.

Pumping or compressing of the fluid by reciprocation of a plunger withina cylinder bore having either closed or selectively closed ends is wellknown in the art. One of the conventional means of affecting the plungerreciprocation is the helical winding of two distinct solenoid coilsabout the cylindrical member, with the inner ends of the two coils beingslightly longitudinally spaced apart. Reference may be made to theHeftye U. S. Pat. No. 581,204; Winsor U. S. Pat. No. 1,840,994; Cobe U.S. Pat. No. 1,974,262; and Marini, U. S. Pat. No. 3,196,797 fordisclosures of electromagnetic piston pumps having axially spacedsolenoid coils.

This type of pump can be adapted to given functional requirements byvarying the dependent design parameters of piston stroke length,reciprocation rate, and pumping force. If such a pump has a relativelysmall piston compared to the axial size of the cylinder and coils, thelines of magnetic force for the remote coil must travel increaseddistances to pull the plunger therewithin. Accordingly, any increase inthe stroke for such a piston results in a decrease in both effectivemagnetic force and plunger reciprocation rate. If, however, the pistonis relatively long and extends to a position radially within each of thecoils, the increased weight of the piston and the residual magneticforce field present result in reducing piston reciprocation rate whilealso reducing braking efficiency at the end of the stroke.

Accordingly, it is the principal object of the present invention toprovide a positive displacement electromagnetic piston pump, or motordevice, having axially spaced solenoid coils which increases pumpingforce and displacement capabilities over that available in aconventional motor and pump tandem of substantially equal size andstroke length. This object is accomplished by providing a pistonassembly having two axially spaced piston members joined together by anonmagnetic spacer or coupling, such piston assembly being of sufficientaxial extent to maintain at least a portion of both pistons radiallyinside the solenoid coils irrespective of the axial position of thepiston assembly within the cylinder bore.

Another important object of the present invention is to provide a fluidcontrol system in association with the electromagnetic piston assemblypump that is responsive to reciprocal movement of the piston assemblysimultaneously to draw and pump such fluid during both forward andreturn movements of the piston assembly.

It is another object of the present invention to provide anelectromagnetic pumping or compressing device that may be readilydismantled for maintenance or replacement of any of the parts. Suchobject is accomplished by the provision of removable but neverthelessaccurately positioned solenoid coils and removable valve plateassemblies operative selectively to close off the ends of the cylinderbore.

Other objects and advantages of the present invention will becomeapparent as the following description proceeds.

To the accomplishment of the foregoing and related ends the invention,then, comprises the features hereinafter fully described andparticularly pointed out in the claims, the following description andthe annexed drawing setting forth in detail a certain illustrativeembodiment of the invention, this being indicative, however, of but oneof the various ways in which the principles of the invention may beemployed.

In said annexed drawing:-

FIG. 1 is an elevation partially broken away and in section showing thepiston assembly of the invention in its centered position; and

FIG. 2 is an elevation similar to FIG. 1 showing the piston assembly atthe end of its right-hand stroke.

Referring now in more detail to the drawings and initially to FIG. 1,the electromagnetic pump or motor device of the present inventionincludes a cylinder indicated generally at l, the piston assemblyindicated generally at 2, and two solenoid coils indicated at 3 and 4.The cylinder has an .open ended bore 5 and is made from a non-magneticmaterial, such as nylon, ceramic, or Teflon, that is compatible with thefluid being pumped. Cylinder 1 has a central, radially outwardlyextending annular projection or rib 7 which forms two annular stop faces8 and 9.

Two conventional solenoid coils 3 and 4 are wound within annularhousings 11 and 12, respectively, with the inner diameter of such coilsbeing substantially equal to the outer diameter of cylinder 1. The coilsare accurately but removably positioned in the axially spacedrelationship shown by sliding the same axially inwardly until flange 14on housing 11 or flange 15 on housing 12 abut stop faces 8 or 9,respectively. The coil housings are made of laminated magnetic materialwhich lamination operates to conduct magnetic lines of flux towardcylinder 1 while breaking up any eddy currents. The housings withincluded coils may be held in assembled or operative condition by anytype of nonmagnetic end stops l8 removably positioned against theaxially outer walls of the same, whereby upon radial wqthdrawal of suchshoulders coils 3 and 4 may be readily removed from the cylinder formaintenance or replacement. A conventional electric circuit (not shown)is provided alternately to energize coils 3 and 4 to produce separatemagentic fields.

The respective magnetic fields are operative alternately to attractpiston assembly 2 resulting in reciprocatory axial movement of the samein bore 5. The piston assembly includes two spaced apart cylindricalpiston members 19 and 20 joined together in axially spaced relationshipby a connecting pin 21. The pistons 19 and 20 are of slightly smallerdiameter than bore 5 and are sealed to the inside surface of cylinder 1for sliding movement by piston rings 22 preferably made from a Tefloncompound or the like. The cylindrical pistons are made of a magneticmaterial having a coating thereon compatible with the fluid being pumpedand may be hollow to reduce the weight of the assembly.

The connecting pin 21 is made from a non-magnetic material such asnylon, ceramic or a Teflon compound. The length of the connecting pinand thus the spacing between piston members 19 and 20 may be varied inaccordance with the piston stroke desired and the spacing of the coils.In other words, with a predetermined spacing of the coilsand a desiredpiston stroke, the length of the connecting pin needed may readily bedetermined. Such pin or coupling must be of sufficient length, however,to result in piston assembly 2 being of sufficient axial extent toposition a portion of piston members 19 and 20 radially inside coils 3and 4, re spectively, irrespective of the position of such pistonassembly in bore 5.

The ends of cylinder 1 and consequently bore are closed off andselectively sealed by valve plate assemblies indicated generally at 25.Such assemblies 25 are made from non-magnetic materials and may bepressfitted into the cylinder or attached by conventional fasteningmeans. The fastening means for the valve plate assemblies may be of apermanent or temporary nature, the latter type of fastener permittingremoval of the valve plate assemblies for maintenance purposes. At theends of bore 5, two fluid chambers of variable volume 26 and 27 areformed by pistons 19 and 20, respectively, cylinder 1, and valve plateassemblies 25.

Referring in detail to the valve plate assembly at the right end of thepumping device as viewed in FIG. 1, valve plate 29 has a peripheralinner shoulder 30 which receives the end of cylinder 1 properly to seatsuch valve plate with respect to the cylinder. Two diametrically offsetbores or passages 31 and 32 extend axially through valve .plate 29 tocommunicate at their inner ends with fluid chamber 27. Check valves 33and 34 are connected to plate 29 by suitable fastening means and coverthe inside and outside ends of bores 31 and 32, respectively. Such checkvalves normally block fluid flow through such passages and areeffectively oppositely biased since valve 33 when open permits fluidflow into chamber 27 while valve 34 when open permits fluid flow fromchamber 27. A T-shape adaptor member 36 is connected to the outsidesurface of plate 29 andis formed with an inlet passage 37 and an outletpassage 38, such passages being in fluid communication with bores 31 and32, respectively.

The left-hand valve plate assembly is substantially identical to and amirror image of the right-hand valve plate assembly just described andincludes plate 40 with offset axial bores 41 and 42 extendingtherethrough. Such bores are normally closed by oppositely biased checkvalves 43 and 44, respectively. Adaptor member 46 defines inlet andoutlet passages 47 and 48 which are selectively in fluid communicationwith bores 41 and 42, respectively.

It will be appreciated that conduits or tubing in the fluid flow systemmay be attached to the ends of adaptor members to complete thesealed andclosed pumpingor compressing device. In atypical refrigerationapplication of the device, conduits attached to inlet passages 37 and 47emanate from the evaporator, while conduits connected to outlet passages38 and 48 lead to the condenser.

A cycle in the operation of the electromagnetic pumping device of thepresent invention can best be described in context with FIG. 2. Theenergization of coil 4 creates a magnetic field causing piston to becomemagnetized and the action of the field in the solenoid on the polescreated on piston 20 results in the entire piston assembly movingrapidly to the right in the bore to a position in which piston 20 iswithin coil 4 at the center of the field of force. The centering of thepiston 20 within the field acts as a magnetic damper or brake on theentire piston assembly, with plate 29 being slightly set back from theend of the stroke to preclude contact between the piston and valve plateassembly.

The forward stroke of the piston effected by energization of coil 4compresses the fluid contained within chamber 27 and pushes the fluidthus compressed through check valve 34 into the fluid flow system asindicated by arrows A. The increased pressure of such fluid is greaterthan the inlet fluid pressure in passage 37, whereby check valve 33remains in the normally seated position shown. At the same time, thevolume of chamber 26 is proportionately increased by the piston assemblymovement to develop a low or negative sealed pressure zone in suchchamber. This low pressure is less than the pressure in the fluid flowsystem whereby check valve 43 is opened to allow entry of fluid throughinlet bore 41 as indicated by arrows B, and check valve 44 is seated topreclude delivery of such fluid through passage 42. At the completion ofthe forward stroke, a portion of piston 19 remains radially inside coil3 and therefore within a potentially strong magnetic force field.

Thus when coil 4 is deenergized and coil 3 substantially simultaneouslyenergized by the electrical circuit, the magnetic force field of coil 3will quickly pull magnetized piston 19 and thus piston assembly 2 to theleft until the centering effect of piston 19 and coil 3 stops suchplunger to complete the piston assembly cycle. Thus the reciprocalmovement of the piston assembly is quickly and smoothly effected withoutcomplicated electrical systems, springs, end stops or mechanicallinkages. The return stroke of the piston assembly cycle has theopposite effect onthe valves shown, specifically, check valves 33 and 44will open, while check valves 34 and 43 will close. Such disposition ofthe valves enables the device to draw fluid into chamber 27 throughinlet port 33 and to deliver compressed fluid from chamber 26 to outletpassage 44.

The present invention thus permits rapid cyclical movement of the pistonassembly since the piston members are always positioned in astrong forcefield. Moreover, the spacing of the coils and piston members and thenon-magnetic cylinder eliminate any sticking or hesitancy in initiatingreverse movement which might be caused by residual magnetic forcefields.

The present electromagnetic device may be used in any type ofenvironment requiring reciprocal movement of a piston assembly and is,of course, not limited to the specific embodiment shown. For example, apiston rod or saw blade could be connected to the plunger to extendaxially beyond the cylinder member.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:

1. An electromagnetic pump or motor device compirising a housing havinga bore therein, spaced solenoid coils about said housing adaptedalternately to be energized, piston means movable in the bore, saidpiston means including two piston members axially separated by anon-magnetic spacer member of sufficient extent to position at least aportion of both pistons radially inside the solenoid coils irrespectiveof the axial position of the piston means within the bore, whereby, whensaid coils are alternately energized to produce respective magneticfields, said piston means is alternately magnetically attracted toreciprocate within said bore.

2. The pump set forth in claim 1 wherein the coils are removable fromsaid housing but are accurately held in predetermined axially spacedpositions during operation.

3. The pump set forth in claim 2 wherein the housing has anintermediate, radially outwardly projecting rib to form stop facesagainst which the axially inner ends of the two coils abut accurately toposition the same.

4. The pump set forth in claim 1 wherein the housing and coils aregenerally cylindrically formed with the inside diameter of the coilsbeing approximately equal to the outside diameter of the housing,whereby the coils may be slid onto and off of said housing.

5. The pump set forth in claim 4 further including means to position andhold the coils in axially spaced relationship during operation.

6. The pump set forth in claim 5 wherein the means to position and holdincludes an intermediate outwardly projecting rib on said housingforming axially spaced stop faces against which the inner ends of saidcoils abut accurately to position the same.

7. The pump set forth in claim 6 wherein the means to position and holdincludes removable stops against the outer ends of the coils to maintainaccurate positioning of such coils during operation.

8. The pump set forth in claim 1 further including end plates associatedwith said housing to close off the ends of said bore, said end platesselectively communicating with a fluid intake and delivery system.

9. The pump set forth in claim 8 wherein each of the end plates isremovable from the bore and includes two oppositely biased check valves,one of such valves communicates with the fluid intake line of the systemwhile the other valve communicates with the fluid delivery line of thesystem. 1k t

1. An electromagnetic pump or motor device compirising a housing havinga bore therein, spaced solenoid coils about said housing adaptedalternately to be energized, piston means movable in the bore, saidpiston means including two piston members axially separated by anon-magnetic spacer member of sufficient extent to position at least aportion of both pistons radially inside the solenoid coils irrespectiveof the axial position of the piston means within the bore, whereby, whensaid coils are alternately energized to produce respective magneticfields, said piston means is alternately magnetically attracted toreciprocate within said bore.
 2. The pump set forth in claim 1 whereinthe coils are removable from said housing but are accurately held inpredetermined axially spaced positions during operation.
 3. The pump setforth in claim 2 wherein the housing has an intermediate, radiallyoutwardly projecting rib to form stop faces against which the axiallyinner ends of the two coils abut accurately to position the same.
 4. Thepump set forth in claim 1 wherein the housing and coils are generallycylindrically formed with the inside diameter of the coils beingapproximately Equal to the outside diameter of the housing, whereby thecoils may be slid onto and off of said housing.
 5. The pump set forth inclaim 4 further including means to position and hold the coils inaxially spaced relationship during operation.
 6. The pump set forth inclaim 5 wherein the means to position and hold includes an intermediateoutwardly projecting rib on said housing forming axially spaced stopfaces against which the inner ends of said coils abut accurately toposition the same.
 7. The pump set forth in claim 6 wherein the means toposition and hold includes removable stops against the outer ends of thecoils to maintain accurate positioning of such coils during operation.8. The pump set forth in claim 1 further including end plates associatedwith said housing to close off the ends of said bore, said end platesselectively communicating with a fluid intake and delivery system. 9.The pump set forth in claim 8 wherein each of the end plates isremovable from the bore and includes two oppositely biased check valves,one of such valves communicates with the fluid intake line of the systemwhile the other valve communicates with the fluid delivery line of thesystem.